The present invention relates to a vehicle having an internal combustion engine and a waste-heat collecting housing.
German patent document DE 4441351 A1 discloses a vehicle having a latent heat accumulator in which, when the vehicle is parked, heat can be stored, said heat permitting more rapid heating up of the passenger compartment following a cold start of the vehicle. The latent heat accumulator is connected to the cooling circuit of an internal combustion engine of the vehicle and can accordingly be “charged” with heat from the cooling circuit of the internal combustion engine. If the internal combustion engine is “cold”, heat can be output from the heat accumulator into the cooling water, and therefore the internal combustion engine more rapidly reaches its normal operating temperature. Following a “cold start” of the vehicle, the passenger compartment can also be heated up comparatively rapidly by the heat stored in the heat accumulator, i.e., without the internal combustion engine already having to have reached its full operating temperature.
It is an object of the invention to provide a vehicle in which heat output by the internal combustion engine in another manner (i.e., not via the cooling circuit) can be used, in particular for storing in a heat accumulator.
The starting point of the invention is a vehicle having an internal combustion engine and an exhaust manifold via which hot exhaust gas coming from the internal combustion engine is introduced in an engine-side portion of an exhaust system. The term “engine-side portion” of the exhaust system comprises in particular the portion between the exhaust manifold and a portion of the exhaust system that adjoins the engine-side portion and runs in the underbody region of the vehicle.
An essential concept of the invention consists in that, by use of a waste-heat collecting housing which surrounds or encloses at least part of the exhaust manifold and/or part of an engine-side portion of the exhaust system, the air contained in the exhaust gas collecting housing is heated. The transfer of heat from the exhaust manifold and/or the engine-side portion of the exhaust system to the air contained in the waste-heat collecting housing takes place via heat radiation and convection.
The heated air can be used indirectly, for example via a heat accumulator, or else directly, for heating air which is introduced into a passenger compartment of the vehicle.
For thermal reasons, it can be provided that the waste-heat collecting housing is at least partially, in particular largely, composed of metal sheet. As an alternative thereto, the waste-heat collecting housing can also be produced from a sufficiently thermally stable plastics material.
As already explained, the waste-heat collecting housing surrounds at least part of the exhaust manifold or the entire exhaust manifold and/or at least part of an engine-side portion of the exhaust system. In particular, it can be provided that at least one catalytic converter of the exhaust system is arranged within the waste-heat collecting housing. The catalytic converter can be, for example, an NOx storage catalytic converter, an SCR catalytic converter (catalytic converter for carrying out selective catalytic reduction) or the like.
Alternatively or additionally thereto, it can be provided that an exhaust gas turbocharger or at least one turbine-side region of the exhaust gas turbocharger is arranged within the waste-heat collecting housing.
According to a development of the invention, the waste-heat collecting housing has an air inlet via which air can flow from the surroundings or from an engine compartment of the vehicle into the waste-heat collecting housing. After the operating temperature of the internal combustion engine is reached, the air located in the engine compartment is warmer than the ambient air and, after flowing into the waste-heat collecting housing, is heated further by the from the exhaust manifold and/or the engine-side portion of the exhaust system.
According to a development of the invention, the waste-heat collecting housing has at least one first air outlet for heated air. It can be provided that the first air outlet is thermally connected via an air duct to a heat accumulator, wherein the heated air coming from the waste-heat collecting housing outputs heat to the heat accumulator.
The term “heat accumulator” is understood as meaning a device which is provided and is suitable for storing heat for a prolonged period, in particular for a period of more than one day. The heat accumulator contains a heat transfer agent or a heat transfer medium which is accommodated in a housing of the heat accumulator. The housing is thermally insulated toward the outside, as a result of which heat losses into the environment are minimized.
The heat transfer agent can contain in particular a “phase change medium,” i.e., a medium which makes a phase transfer between the states of “heat accumulator charged” and “heat accumulator discharged.” Heat accumulators of this type are also referred to as “latent heat accumulators.” They can be used to store heat in a vehicle parked for a prolonged period, said heat then being available just a few seconds following a cold start of the vehicle in order to heat the passenger compartment and/or in order to preheat the internal combustion engine of the vehicle.
In comparison to conventional vehicles having a heat accumulator, in which the heat accumulator is coupled thermally to a cooling circuit of the internal combustion engine, the arrangement according to the invention is substantially more simple and more cost-effective.
According to a development of the invention, the exhaust gas collecting housing has at least one second air outlet via which air heated in the exhaust gas collecting housing can be directly removed, bypassing the first air outlet and the heat accumulator, to the environment. If the heat accumulator is “Charged up” to a maximum or approximately to a maximum with heat, it may be expedient to remove the air heated in the exhaust gas collecting housing directly to the environment.
Furthermore, a fan can be provided which, in the exhaust gas collecting housing, produces an air flow directed toward the first and/or the second air outlet. In other words, by use of a fan of this type, air can be sucked in via the air inlet of the waste-heat collecting housing or air can be blown in via the air inlet. As already indicated, the air can be sucked or blown into the waste-heat collecting housing from the environment or from the engine compartment of the vehicle.
The fan can be arranged within the waste-heat collecting housing. As an alternative thereto, it can also be arranged in the region of the air inlet.
According to a development of the invention, an exhaust air duct is provided via which cooled air coming from the heat accumulator can be removed to the environment.
According to a development of the invention, a first heat exchanger is provided via which heat can be transferred from the heat accumulator to the air to be introduced into a passenger compartment of the vehicle. If the heat accumulator is filled with a liquid heat transfer medium, the first heat exchanger can be a liquid/air heat exchanger. If the heat accumulator is filled with a gaseous medium, the heat exchanger can be a gas/air heat exchanger. The first heat exchanger can be accommodated together with the heat accumulator in a common housing.
Alternatively or additionally thereto, a second heat exchanger (air/air heat exchanger) can be provided via which heat from the air heated in the waste-heat collecting housing can be directly transferred to the air to be introduced into the passenger compartment of the vehicle, with the heat accumulator being bypassed.
Furthermore, a valve or flap arrangement which can be controlled by an actuator system can be provided, wherein, depending on the position of the valve or flap arrangement,                the entire air flow coming from the waste-heat collecting housing is conducted via the first air outlet and the heat accumulator into the environment (wherein heat is stored in the heat accumulator) or        the entire air flow coming from the waste-heat collecting housing is conducted, bypassing the first air outlet and the heat accumulator, directly into the environment, or        a first partial volumetric flow of the air flow coming from the waste-heat collecting housing is conducted into the environment via the first air outlet and the heat accumulator (wherein heat is stored in the heat accumulator), and a second partial volumetric flow of the air flow coming from the waste-heat collecting housing is conducted into the environment, bypassing the first air outlet and the heat accumulator.        
Conducting all of the air flow coming from the waste-heat collecting housing into the environment via the first air outlet and the heat accumulator is expedient if the heat accumulator is completely or substantially discharged or if it is not yet completely charged. Conducting all of the air flow coming from the waste-heat collecting housing directly into the environment, with the heat accumulator being bypassed is expedient if the heat accumulator is virtually or completely “charged”.
The above-described “mixed mode” (third dash in the list) may be expedient if the heat accumulator is already partially charged.
According to a development of the invention, the actuator system has an electric actuator, for example in the form of a stepping motor or the like.
It can be provided that the valve or flap arrangement has an unactuated basic position in which the entire air flow coming from the waste-heat collecting housing is conducted, bypassing the heat accumulator, into the environment. The valve or flap arrangement can be prestressed into the unactuated basic position, for example by a spring arrangement. It is thereby ensured that, in the event of a malfunction or a failure of the actuator system, the valve or flap device merges into the unactuated basic position. Overheating of the heat accumulator is thereby reliably prevented.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.